Need advice for B&W 804 diamond amplification

B&W - it's ALWAYS Rotel, McIntosh, and Classe. Why is that. Hmmmm...every dealer I've ever been to that sells B&W sells either Rotel and McIntosh or Rotel and Classe. Has anyone ever tried with another amp?

I have the 804 Diamonds ("D2") as well. I have been evaluating them with my Audio Research 100.2 Solid State amp and Bel Canto Pre2 Preamp, which I highly recommend. While I have been listening I've been looking at other options in the event my 100 w/ch amp was not enough, and mostly out of curiosity really. The 100.2 is rated down to 2 ohms at 360 w/ch. In my research I noted that many amps were not rated below 4 ohms (per the B&W website the diamond speakers dip to 3 ohms). Anyway, after doing a lot of listening, and a lot of web searching, I'm not sure I want to change anything. The 100.2 is quite a fantastic amp, as many of the reviews here on Audiogon and elsewhere will tell.
One thing with the new diamond series is that the treble is very revealing, and I could see where it might get fatiguing with a bad match in electronics. At the same time, the ARC 100.2 is known for its treble quality. I have found that the two are an excellent match in that area. The ARC/B&W combination is very detailed while remaining crystal clear and not harsh. There is a slight warmth overall in the midrange on down, and I think both the speakers and the amp are known for this, and it is complimentary to the clarity and detail in the same range. Bass is very good. As an aside, I think people who criticize the bass on the nautilus series in general are not understanding what good quality bass sounds like...anyway, I digress...
If anything, I think if I needed more power I would just get another 100.2 and bi-amp vertically. The Bel Canto Pre2 is nice in that it offers two sets of balanced pre-outs, so you can do this. Overall this combination of preamp and amp is quite excellent – what would have set you back over $7k eight years ago can be had for about 2,500 now, and I think I would be hard pressed to do a lot better.
In the mean time I will keep listening and report back later. So far I have not even put the 804’s up on the included spikes, or Sound Anchors I bought for them, and still need to play around with position some more. But already they sound VERY good overall. Overall though I would say the ARC is a really good combination with the 804’s. ARC has some newer SS amps as well that are not Class D (such as the SD-135 and HD-220) that may be a good match as well. By the way, room size is 15’ by 24’ with 8 foot ceilings. I plan to move to a smaller space, which is why I bought these.
As far as frame of reference, I have never owned Classe but have had McIntosh MC-300 and MA-6900, and Rowland Concentra and Concerto. The MC-300 was very good with the Matrix 802’s I owned at the time. I would not put down McIntosh in any way, but personally I would not buy it new for the price. I would love to hear a Rowland Concentra II with these speakers. Otherwise, something like the Classe CA-2200 would be good to try, though some of their older amps (like the CA-101 ?) used for $700 or so also vertically bi-amped with a good preamp would probably get you a great value for the dollar. Some people have to have the latest gear, but it seems a lot of the older amps from many of these manufacturers have greater power/current down to 2 ohms, while the newer models are not rated at 2 Ohms. Not sure if it really matters, but having owned several pairs of B&Ws over the years I have found it true that they really seem to open up with more power.

By the way, I should have mentioned in regards my first post, I have nothing against McIntosh, Classe, or Rotel, just tired of seeing that nearly every post on the web you can find on newer B&W speakers seems to involve these manufacturers, and I can not believe that people are not using something else somewhere out there (which is why I posted my lengthier post on my experience with the ARC gear). Also, I will note that I have owned Rotel in the past with great results, and actually heard the 804 D2's with Rotel's 70w/ch integrated and was very impressed.